The present invention relates to a device and method ergonomically suitable for users for reading a code, such as a bar code, on, or scanning of, an article, wherein radiation is projected onto the article, from two sides, thereby preventing the person holding the article from having to turn it with awkward wrist movements.
Such devices are per se known, and the present invention has for its object to improve this invention, particularly in the sense that interruption of the reading process at the end of the lifespan of the laser is precluded and/or further possibilities are created by making wavelengths and/or focus points of both radiation sources mutually different.
The present invention comprises a device for reading a code on an article, comprising:
a housing provided with at least two windows for passage of radiation which are disposed at a relative mutual angle;
radiation source means for transmitting radiation to the article, which radiation source means are arranged in the housing and comprise at least two separate radiation sources;
a rotatable polygonal mirror for reflecting radiation coming from the radiation source means;
a number of fixedly disposed mirrors for reflecting through the respective windows the radiation coming from the polygonal mirror; and
detection means for detecting the radiation scattered by the code.
In the preferred embodiment wherein the radiation sources each transmit radiation of a different wavelength, it is possible in the case that one of the two wavelengths has difficulty in distinguishing the bar code from the background that the code can still be recognized using other wavelengths.
As a result of the preferred embodiment wherein each of the radiation sources is focussed at a different distance relative to the window, the area within which bar codes can be effectively scanned is enlarged.
The present invention further provides a method wherein the device according to the present invention is applied.
In each of the two above stated preferred embodiments the scanning potential is increased, whereby the movement of the article during the scanning movement by for instance a check-out operator requires the least possible adjustment, whereby the ergonomics are improved further.
In a further preferred embodiment the radiation sources each have a different polarization direction. In many cases the material of the bar code is sensitive to the polarization of the incident laser light such that a stronger reflection is obtained for one of the two radiation sources. It is then possible to take into account in the microprocessor for which polarization direction the best score of bar code recognition is obtained so that this can be switched ON more often than the other radiation source.
As much use as possible is preferably made of symmetrical scan patterns since, from a statistical viewpoint, there is no preference for the direction of the bar code. The scan lines are projected alternately whenever possible through each of the two windows. This further enables the use of the same components for a horizontal and a vertical window with fixed mirrors. It is however possible to suffice with a single polygonal mirror and sensor with associated analog electronics.
Finally, the present invention provides a number of co-acting devices according to the present invention, whereby a passage is obtained for scanning articles on all sides, for instance articles supplied on a conveyor.